[c-nsp] Varying CPU usage on 881

[Rodney Dunn]

That does look strange then if it's a constant rate of traffic
from a test box going through the router. Probably an issue with
how the box measures the CPU usage.

Can you open a TAC SR and have the TAC engineer recreate it in the lab
and file a bug on it?

On Mon, Sep 29, 2008 at 04:20:04PM +0200, Pelle wrote:
> Hi Rodeney.
> 
> > That graph is total usage so there may be another process that
> > contributes that takes longer on the 881 that doesn't show up
> > on the 1841. ie: checkheaps, etc...
> >
> > Watch 'sh proc cpu sorted' during one of those spikes and see
> > if you see another process contributing.
> 
> That was my original theory as well, but there are no other
> significant processes:
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 23%/18%; one minute: 14%; five minutes: 5%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1104       514       2147  2.21%  0.69%  0.23%   6 Virtual Exec
>   60        4208       632       6658  3.19%  2.67%  1.06%   0 COLLECT STAT COU
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 23%/18%; one minute: 14%; five minutes: 5%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1136       519       2188  2.21%  0.69%  0.23%   6 Virtual Exec
>   60        4260       639       6666  3.19%  2.67%  1.06%   0 COLLECT STAT COU
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 43%/40%; one minute: 16%; five minutes: 6%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1168       524       2229  1.31%  0.74%  0.25%   6 Virtual Exec
>   60        4292       644       6664  1.88%  2.61%  1.07%   0 COLLECT STAT COU
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 43%/40%; one minute: 16%; five minutes: 6%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1200       529       2268  1.31%  0.74%  0.25%   6 Virtual Exec
>   60        4332       650       6664  1.88%  2.61%  1.07%   0 COLLECT STAT COU
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 43%/40%; one minute: 16%; five minutes: 6%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1228       534       2299  1.31%  0.74%  0.25%   6 Virtual Exec
>   60        4372       656       6664  1.88%  2.61%  1.07%   0 COLLECT STAT COU
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 43%/40%; one minute: 16%; five minutes: 6%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1260       539       2337  1.31%  0.74%  0.25%   6 Virtual Exec
>   60        4404       661       6662  1.88%  2.61%  1.07%   0 COLLECT STAT COU
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 27%/23%; one minute: 17%; five minutes: 6%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1292       544       2375  1.63%  0.82%  0.27%   6 Virtual Exec
>   60        4484       673       6662  2.78%  2.62%  1.10%   0 COLLECT STAT COU
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 27%/23%; one minute: 17%; five minutes: 6%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1324       549       2411  1.63%  0.82%  0.27%   6 Virtual Exec
>   60        4532       680       6664  2.78%  2.62%  1.10%   0 COLLECT STAT COU
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 27%/23%; one minute: 17%; five minutes: 6%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1360       554       2454  1.63%  0.82%  0.27%   6 Virtual Exec
>   60        4572       686       6664  2.78%  2.62%  1.10%   0 COLLECT STAT COU
> 
> 881_router#sh proc cpu | ex 0.00
> CPU utilization for five seconds: 21%/17%; one minute: 18%; five minutes: 6%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   51        1396       559       2497  1.72%  0.89%  0.30%   6 Virtual Exec
>   60        4612       692       6664  2.62%  2.62%  1.12%   0 COLLECT STAT COU
> 
> (The captures are taken quite rapidly.)
> 
> It's the sudden peak from 18% to 40% and back down to 17% for the
> _interrupt based traffic_ that puzzles me.
> 
> > Also, I don't think it applies here given the pps number you gave
> > before.
> >
> > I usually see that when the rate is divisible by 4.
> 
> The same wavy CPU load occurs whatever traffic I throw at the router.
> 
> -- 
> Pelle
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